Hydrazine based solid propellants



HYDRAZINE BAS Henry Philip Heubus PROPELLAN TS ce Corporatlo 20, 1964, Ser. No

eing a continuacopending application Ser. No. 835,387

9, now abandone energy but the disadva to high corrosiveness,

The solid prop time been reco and extremely high chemiellants, or gas generants,

have for some gnized as being more desiraand pyrotechnic fields as for p It is therefore an object methods for the production 0 f this invention to provide f new and useful gas generof this invention to provide new compositions for use in reaction ntion is to provide new c materials which give outstanding when used as fuels. e present invention, polymers are group having an inorganic with such amino group nitrogen atom contained within the sically, there are three systems ac t'invention; one in which a polymer racteristic is first formed azine derivative, whereaf acid is added to the formed in situ from unsaturated hydrazine derivative acid; and one in which the ove characteristics is formed re of a hydroxy alkyl hydrational compound, and an inove characteristics is a starting mixture of an and an inorganic oxidi polymeric salt having t in situ from a starting mixtu zine compound, a polyfunc organic oxidizing acid.

g acid may be perchloric acid, nitric acid,

sulfuric acid, hosphon'c acid and mixtures thereof; al-

Patented Apr. 18, 1967 though it is preferred to use perchloric acid due to its richness in oxygen.

To illustrate this system, such derivatives as N-aminoethyleneimine (three membered ring), 3-amino-2-oxazolidinone (five rnembered ring), and the like may be used such polymer having the following structural formula:

Although the method of making polyethylene hydrazine forms, per se, no part of the present invention, a preferred method for obtaining this polymer is by the decarboxylation of 3-amino-2-oxazolidinone. Specifically, 3-amino-2-oxazolidinone 1S decarboxylated by continued heating at 210 C. until the evolution of carbon dioxide has diminished as is indicated by repeated collapsing of the foaming product. At this point, the product is cooled quickly to room temperature and, thereafter, the product is maintained at a temperature of 105 C. for twenty-four hours and under a vacuum of 0.1 mm. of mercury. The resultant polymer, polyethylene hydrazine, has a molecular weight of about 700, a density of 1.3 grams per cc. and a softening point of about 90 C.

Example I Polyethylene hydrazine, which may be prepared as specified above, is formed into a slurry with a suitable taining the temperature of the products below C., perchloric acid is added to the above slurry, with stirring. The perchloric acid is added in the ratio of 2.0 moles of After all of the perchloric acid has been added, the reaction product is brought to room temperature and and its combustion efiiciency exceeds The product reaches a softening point at about C. and reaches an auto-ignition point at about C. and exhibits an in which at is approximately 0.8 and n is 4.

Although the monopropellant possesses a high burning rate as described above, its sensitivity to impact is comparable to conventional operational propellants. Specifically, the present monopropellant exhibits reaction to the impact of an 80 oz. weight dropped from a height of about 6 inches not more than one out of ten times. In the preparation of the monopropellant as specified hereinabove, the amount of agitation at room temperature subsequent to the initial reaction between the perchloric acid and polyethylene hydrazine may be as little as 0.2 hour. Tests indicate no difference in the monopropellant obtained after 0.2 hour of agitation and that obtained after hours of agitation, indicating that the monopropellant according to the present invention may be commercially prepared in continuous fashion.

Example 11 Example I11 Example I is repeated except that sulfuric acid is substituted for perchloric acid.

The polymeric salts of Examples II and III yield results similar to those obtained in Example I, demonstrating the practicality of using different inorganic oxidizing acids. As stated hereinbefore, the use of perchloric acid is preferred due to the high oxygen content of this particular acid.

In the second system mentioned above (polyenes), the unsaturated hydrazine derivative must contain at least one double bond between carbon atoms, necessitating that the unsaturated compound contain at least two carbon atoms while practical considerations involving availability of starting compounds dictates that the unsaturated derivative may contain up to eight carbon atoms.

Example IV To one mole of an aqueous solution of monomethallyl hydrazine CH =C(CH )CH NHNH is added one mole of sulfuric acid. The resulting solution is vacuum distilled at 70 C. and 0.3 p.s.i.a. for 2 hours to remove water; the temperature is then increased to about 125 C. at a pressure of 3 p.s.i.a. for several hours until a brown, thermoplastic polymer results.

Example V To one mole of an aqueous solution of unsymmetrical diallyl hydrazine is added one mole of sulfuric acid. The resulting solution is refluxed at atmospheric pressure for 8 hours and the product is isolated by vacuum distillation at elevated temperature. Specifically, starting from 100 C. and 0.2 p.s.i.a., the temperature is gradually increased to 190 C. until a red-brown thermoplastic polymer is formed.

Example VI Example V is repeated except that nitric acid is substituted for the sulfuric acid, yielding similar results.

It is interesting to note that in Examples 1V, V and VI, the inorganic oxidizing acid acted as a catalyst as Well as providing the oxidizer function in the monopropellant combination. Moreover, attempts to effect polymerization of the unsaturated hydrazine compound were unsuccessful when conventional catalysts such as benzoyl peroxide, tertiary butyl hydrogen peroxide, ferric chloride and the like were used.

The third class mentioned above (polyesters) involves the condensation of a hydroxy alkyl hydrazine with a polyfunctional compound selected from the group consisting of (CH )x(COO H) (CH )x(COY) (CH )x(CO0R) and (CH )x(CO) O*, where x is O to diethanol hydrazine (HOCH CH NNH Example VII To one mole of an aqueous solution of unsymmetrical is added one mole of oxalic acid and one mole of sulfuric acid. The resulting solution is refluxed at atmospheric pressure for 8 hours, yielding a red liquid. Water is then removed by vacuum distillation at C. and 0.2 p.s.i.a. until a dark red thermoplastic polymer forms.

Example V1 11 Example VII is repeated except that unsymmetrical diisopropanol hydrazine (H CCH(OI-l)CH NNH is substituted for the unsymmetrical diethanol hydrazine. A brown thermoplastic polymer results.

It is to be understood that certain changes and modifications may be made without departing from the spirit of the invention or the scope of the following claims.

I claim:

1. A method of making a polymer characterized by its ability to evolve sufficient quantity of gaseous products as to render the polymer useful as a rocket propellant and the like, which comprises forming a slurry of polyethylene hydrazine and a solvent therefor,

adding perchloric acid to said slurry in about the ratio of 2 moles perchloric acid to 1 mole of polyethylene hydrazine, while maintaining the temperature of the mixture below about 25 C.,

agitating the mixture at room temperature and recovering the solid formed.

2. Polyethylene hydrazine perchlorate useful as a solid propellant characterized by its high burning rate combined with high stability and relative insensitivity to impact, having the general structure:

CHt-CHrN where x is about 0.8 and n is an integer.

3. A method of making a polymer characterized by its ability to evolve sufficient quantity of gaseous products as to render the polymer useful as a rocket propellant and the like, which comprises,

forming a slurry of polyethylene hydrazine and a solvent therefor,

adding an inorganic oxidizing acid to said slurry in about the ratio of 2 moles of acid to 1 mole of polyethylene hydrazine, while maintaining the temperature of the mixture below about 25 C.,

agitating the mixture at room temperature and recovering the solid formed.

References Cited by the Examiner UNITED STATES PATENTS 3,211,720 10/1965 Heubusch 149-36 X CARL D. QUARFORTH, Primary Examiner. REUBEN EPSTEIN, LEON D. ROSDOL, Examiners. L. A. SEBASTIAN, Assistant Examiner. 

2. POLYETHYLENE HYDRAZINE PERCHLORATE USEFUL AS A SOLID PROPELLANT CHARACTERIZED BY ITS HIGH BURNING RATE COMBINED WITH HIGH STABILITY AND RELATIVE INSENSITIVITY TO IMPACT, HAVING THE GENERAL STRUCTURE:
 3. A METHOD OF MAKING A POLYMER CHARACTERIZED BY ITS ABILITY TO EVOLVE SUFFICIENT QUANTITY OF GASEOUS PRODUCTS AS TO RENDER THE POLYMER USEFUL AS A ROCKET PROPELLANT AND THE LIKE, WHICH COMPRISES, FROMING A SLURRY OF POLYETHYLENE HYDRAZINE AND A SOLVENT THEREFOR, ADDING AN INORGANIC OXIDIZING ACID TO SAID SLURRY IN ABOUT THE RATIO OF 2 MOLES OF ACID TO 1 MOLE OF POLYETHYLENE HYDRAZINE, WHILE MAINTAINING THE TEMPERATURE OF THE MIXTURE BELOW ABOUT 25*C., AGITATING THE MIXTURE AT ROOM TEMPERATURE AND RECOVERING THE SOLID FORMED. 